Face processing is a pivotal component of human social communication and interaction. A single glimpse of a face yields a tremendous amount of information such as identity, gender, age, race, emotional state, attention, intention, and even veracity. Disordered face processing is believed to underlie a variety of social-cognitive disorders. Thus, neuroscientists have devoted considerable attention to understanding the brain foundations of face processing. Most of this work has focused on brain structures involved in adults' expert level face processing, while little effort has been directed to the questions of how these critical brain systems develop. In contrast to the limited data on the development of brain systems for face processing, an extensive body of work has examined the behavioral changes associated with the emergence of face expertise. That work has shown that expertise in face processing emerges slowly over a long period that begins at birth and extends well into adolescence. Experience and development play a crucial role in establishing mature face expertise. The behavioral studies have also shown that expertise with faces involves change in a number of key processing factors. Among these are the level at which faces are processed (subordinate vs. micro- ordinate/individual), the shift to dominance of configural over featural processing, and more subtly the effects of degree of exposure to different classes of faces. This proposal draws from the extensive body of behavioral data on the development of face expertise to direct our exploration of the development of the neural systems that support face processing in 6- to 15-year-old children. Two projects (five experiments) are proposed. Project 1 provides an in depth examination of change in regional responsiveness and neural networks in the developing brain's spontaneous processing of faces as opposed to objects; thus providing a comprehensive measure of neurodevelopmental change in face expertise. Project 2 examines the influence of process-based factors on the emergence of face expertise. We will use innovative analytical tools to explore functional neural systems across development, in addition to traditional fMRI regional analyses. The knowledge obtained from these studies of typically developing children will advance our understanding of face processing in children with neurological impairments (e.g., autism, developmental prosopagnosia, Williams syndrome, perinatal stroke). This could result in new methods for testing typically developing children and provide standards to assess children in special populations that are at risk for visual processing delays and deficits.